In recent years, a fuel cell system has been proposed which is provided with a fuel cell which directly takes out, as electrical energy, chemical energy resulting from an oxidation-reduction reaction between a fuel gas such as a hydrogen gas supplied to a fuel electrode (anode) and an oxidant gas such as air supplied to an air electrode (cathode).
In such a fuel cell system, a phenomenon is known in which, after the operation of the system is ended, air flows into an anode, so that, for example, carbon carrying catalysts of a separator and the anode is oxidized (hereinafter referred to as carbon oxidation), leading to a reduction in the life of a fuel cell.
In light of the above, for example, in the fuel cell system disclosed in JP2005-100846 A, a technique is proposed in which deterioration of a fuel cell is prevented with the supply of an inert gas to an anode and a cathode when the operation of the system is ended.